SUNDAY, March 29 (HealthDay News) -- The hormone relaxin reduces shortness of breath and cardiovascular death in people with heart failure who also have high blood pressure, according to a phase 2 trial conducted in eight countries.

The study included 234 people who, within a few hours of arriving at a hospital, were randomly assigned to receive an intravenous infusion of a placebo or varying doses of relaxin -- 10, 30 100 or 250 micrograms/kilogram (µ/kg) -- a day.

Shortness of breath improved in 40 percent of those who were given 30 µ/kg, compared with 23 percent of those who received the placebo.

After 60 days, fewer people given 30 µ/kg of relaxin had died from a cardiovascular cause or had to be readmitted to the hospital because of heart or kidney failure than in the placebo group: 2.6 percent compared with 17.2 percent. After 180 days, there were no cardiovascular deaths in the relaxin group at this dosage, but 14.3 percent of the placebo group had died from cardiovascular causes, the study found.

The study also found that people in the relaxin 30 µ/kg group spent less time in the hospital than did those in the placebo group (10.2 days vs. 12 days) and lived longer after discharge (47.9 days vs. 44.2 days). No safety concerns were noted in the relaxin 30 µ/kg group.

The study was funded by Corthera, and several of the researchers worked for the biopharmaceutical company, which has the rights to develop and market relaxin. The findings were to be presented at the American College of Cardiology meeting in Orlando, Fla., and appear online and in an upcoming print issue of The Lancet.

Over time, standard therapy can resolve shortness of breath and high blood pressure caused by heart failure, but evidence from this study "suggests that early administration of this drug in addition to standard therapy might be associated with more rapid, sustained and complete resolution of acute heart failure, as well as with more favorable long-term outcomes," wrote Dr. John R. Teerlink, of the San Francisco Veterans Affairs Medical Center and his colleagues.

On the basis of the study's results, the researchers said they plan to conduct a phase 3 clinical trial of relaxin, at 30 µ/kg, in people with heart failure.